Straight drawing machine

ABSTRACT

Rectilinear drawing machine for drawing material, especially bars, pipes or sections, with at least two movable drawing cars which are driven on a path, one run being assigned to each drawing car, and the runs can be fixed in a variable manner.

BACKGROUND OF THE INVENTION

This invention relates to a rectilinear drawing machine for drawingmaterial, especially bars, pipes or sections, with at least two movabledrawing cars which are driven on a path, one run being assigned to eachdrawing car. The invention relates to a process for continuousrectilinear drawing of drawing material by means of a rectilineardrawing machine with at least two drawing cars, the drawing materialbeing drawn by means of at least one drawing car along a run assigned tothe drawing car on a path.

Such a drawing machine and such a process for rectilinear drawing ofdrawing material are known from publication DE 197 03 878 A1.

In the drawing machine disclosed in this publication, on a path, a firstdrawing car runs, and behind this car, a second drawing car runs, eachare each provided with clamps. While one car at a time is drawing, theother is running with increased speed back into its initial position.When the drawing force is transferred from one car to the other, the twocars are synchronously controlled. For this reason, and due to therelatively great length of the clamps which gently grasp the material,in the transfer of the drawing force, from one car to the other, a fallof the drawing speed is avoided.

The disadvantage of the drawing system described in the indicatedpublication is that invariable lengths of travel are assigned to theindividual drawing cars. This results especially in the fact that acontinuous feed of drawing material, into the drawing machine, is notpossible, or is possible only with great difficulty. So thatspecifically a continuous feed of drawing material into the drawingmachine is possible, the first drawing car must grip the drawingmaterial, spaced so far away from the end of the drawing material thatthe drawing material, when the first drawing car has reached the end ofits run, projects so far into the run of the second drawing car that thesecond drawing car can pick up and continue to draw the drawingmaterial. This is however very complex, since the drawing material, sothat the first drawing car can grasp the drawing material spaced so faraway from the end of the drawing material, must either be drawn by hand,relatively far through the drawing die, or the first drawing car in afirst cycle grasps the drawing material directly at the drawing die,draws it to the end of its run, then travels back to grasp the drawingmaterial again and to draw it in the direction of the second drawingcar.

Therefore it is an object of the invention is to propose a rectilineardrawing machine and a process for operating a rectilinear drawingmachine with which continuous feed of the drawing material into arectilinear drawing machine is easily and quickly possible.

SUMMARY OF THE INVENTION

An object is achieved in that the runs which are assigned to the drawingcars can be fixed in a variable manner. Due to the possibility that theruns of the individual drawing cars are fixed in a variable manner, thedrawing cars can be controlled such that the drawing cars, for feed ofthe drawing material into the drawing machine, are moved as close aspossible to the drawing die in order to pick up the drawing materialwhich has been fed into the machine through the drawing die. Furtherknocking-in, or drawing by hand, thus becomes unnecessary and also feedand regrasping in a first cycle by the first drawing car are thenunnecessary.

The runs of the individual drawing cars can be fixed such that theyoverlap. The runs of the drawing cars can also be changed especiallyduring operation of the rectilinear drawing machine. The rectilineardrawing machine preferably has closed-loop or open-loop control forestablishing the runs.

The object is furthermore achieved in that the drawing cars can bedriven with an electric linear motor. Here it is advantageous if thepath has an inductor and the drawing cars have the armature of thelinear motor. In order to enable operation of the linear motor,according to the principle of a synchronous motor, the drawing cars canbear field coils. Advantageously, the inductor has coils which arearranged along and/or on the path. The rectilinear drawing machine canhave open-loop or closed-loop control via which current flow through theindividual coils which can be controlled independently of one another,by which the runs of the individual drawing cars can be controlled. Thecoils of the inductor can be turned on independently of one another bythe open-loop control, or by the closed loop control, so that a movingfield is formed for each drawing car, by which the drawing car isadvanced. Because the open-loop or closed-loop control dictates themoving fields, the run of the individual drawing cars can be also fixedby the open-loop or closed-loop control. A constructional action intothe drawing machine or modification in the drawing machine is notnecessary to do this. Rather the runs can be fixed during operation ofthe drawing machine by setpoint inputs to the open-loop or closed-loopcontrol.

The drawing cars can be guided mechanically or electromechanically onthe path. The coils of the drawing machine (coils of the inductor, fieldcoils, coils for electromagnetic guidance) can be superconductive. Inparticular, superconductive inductor coils can increase the output ofthe linear motor so much that drawing speeds are possible which areclearly above the drawing speeds achieved to date. This increase ofoutput is otherwise possible when using a linear motor withoutsuperconductive coils compared to the currently conventional drawingmachines with conventional electric motors.

An object is furthermore achieved in that in a process for continuousrectilinear drawing of drawing material the runs of the drawing carsduring drawing are changed. In particular, in a first cycle,specifically during the feed of the drawing material into the drawingmachine, the runs are fixed such that the runs overlap. Then, in theoverlapping area, the end of the drawing material can be transferredfrom the first drawing car to the second drawing car. To transfer thedrawing material, the first drawing car can draw the drawing materialwhich is held beforehand in the area of a drawing die to the start ofthe overlapping area, while there, the second drawing car holds the endof the drawing material and with the first drawing car draws the drawingmaterial to the end of the overlapping area where the first drawing carreleases the drawing material. The second drawing car can then draw thedrawing material to the end of the run of the second drawing car afteraccepting the drawing material from the first drawing car. The run ofthe first drawing car and/or of the second drawing car can be changedafter release of the drawing material by the drawing cars for thefollowing cycles.

In particular, the runs of the drawing cars in the following cyclescannot overlap. The rectilinear drawing machine can have more than twodrawing cars, two drawing cars which are not directly adjacent to oneanother at a time being moved synchronously toward one another on thepath in order to draw the drawing material through the machine. Bysynchronous switching of two or more drawing cars at a time, the pullingforce of the drawing machine can be multiplied so that higher targetoutputs can be achieved.

BRIEF DESCRIPTION OF THE DRAWINGS

One embodiment of the invention is detailed using the drawings.

FIG. 1 shows a side view of a rectilinear drawing machine at the startof feed of the drawing material (first cycle);

FIG. 2 shows the rectilinear drawing machine as shown in FIG. 1 duringthe first cycle, but at a later state of feed;

FIG. 3 shows the rectilinear drawing machine as shown in FIGS. 1 and 2during the first cycle after transfer of the drawing material to thesecond drawing car;

FIG. 4 shows the rectilinear drawing machine as shown in FIGS. 1 and 3in a cycle after feed; and

FIG. 5 shows the velocity-time diagram of the first and the seconddrawing car during one cycle.

DETAILED DESCRIPTION OF THE INVENTION

A rectilinear drawing machine, as shown in FIGS. 1 to 4, has a matrix 1onto which a drawing die 2 is inserted. This drawing die draws a drawingmaterial from a larger cross section to a smaller cross section. To dothis, the drawing machine has a first drawing car 4 and a second drawingcar 5 which are guided on a rod 6. The drawing cars 5 and 6, areprovided with clamps 7 with which the drawing cars grasp the drawingmaterial and draw it through the drawing die 3. The drawing cars 4 and 5furthermore have an iron plate 8 which forms the armature of a linearmotor. The linear motor is completed by coils 9 which form the inductorof the linear motor. The coils 9 are connected by power supply lines 10via an open-loop or closed-loop control unit (not shown) to the powersupply unit. The drawing cars 4, 5 are assigned a run 11, 12.

Before the feed of the drawing material into the rectilinear drawingmachine is described using FIGS. 1 to 3, the operation of therectilinear drawing machine in cycles after feed, i.e. after the firstcycle, will be explained using FIGS. 4 and 5.

The two drawing cars 4, 5 move in a cycle fundamentally in oppositedirections after the first cycle, one car at a time drawing the drawingmaterial over the run, while the clamps 7 hold the drawing material andat the same time the other drawing car with the clamps opened travelsback into its starting position at the start of the run.

The drawing cars 4, 5 are controlled in such a way that when the drawingmaterial 3 is transferred from one drawing car to the other, they runsynchronously with the same drawing speed. This phase of transfer fromthe first drawing car 4 to the second drawing car 5 is labelled withreference numbers 22, 23 in FIG. 5. During the transfer, the drawingmaterial is held for a short time interval in the two drawing cars bythe clamps 7. Immediately after completed transfer the clamps 7 of thefirst drawing car 4 release the drawing material, this car returns withhigh speed while continuous drawing is undertaken by the second drawingcar 5.

In the velocity-time diagram as shown in FIG. 5 of the two drawing carsthe x-axis 20 plots the time t while the y-axis 21 plots the velocity v.The diagram of the first drawing car 4 is shown by solid lines, whilethe diagram of the second drawing car 23 is shown by broken lines. Thephases in which the drawing cars each draw the drawing material throughthe drawing machine are shown by 22 a and 23 a. The phases of thetransfer of the drawing material from the first to the second drawingcar is labeled 22/23. The phase of return of the first drawing car 4from the end of the run 11 to the start 11 a of the run 11 is labeled 22b, while 22 b shows the return of the second drawing car 5 from the end12 b to the start 12 a of the run 12. The tilted flanks of the diagramrepresent the phases of acceleration and deceleration. Horizontalsegments in the diagrams show uniform motion of the drawing cars 4, 5.Here the reference numbers 22 a and 23 a and 22/23 show forward motionfrom the start of one run to its end, while reference numbers 22 b and23 b identify the return trip of the drawing cars 5, 6.

During the continuous drawing, which is described using FIGS. 4 and 5,in cycles after the first cycle, the coils 9 of the inductor aretriggered such that there are two nonoverlapping, directly abutting runs11, 12 for the drawing cars 4 and 5. The moving fields which drive thedrawing cars 4 and 5 and which are produced by the coils 9 of theinductor therefore do not go beyond the start or the end of the runs 11,12.

The feed of the drawing material 3 into the rectilinear drawing machinewill be described at this point using FIGS. 1 to 3. During feed in afirst cycle, the coils 9 of the inductor are triggered such that theruns 11, 12 of the drawing cars 4, 5 overlap. The moving fields arelimited here to the individual runs 11, 12, but can also creep into theregion of the run of the other drawing car. The runs are established bythe open-loop or closed-loop control unit, which is not shown, and whichturns the coils 9 of the inductor on and off such that the desiredmoving field for driving the drawing cars 4, 5 is formed.

In FIG. 1, the drawing cars 4, 5 are each at the start 11 a, 12 a of thelengths of their travel 11, 12. The drawing material 3 is fed through bythe drawing die 2 into the machine and has already been grasped by theclamps 7 of the first drawing car 4. In doing so, the end of the drawingmaterial 3 projects out of the first drawing car 4 in the drawingdirection. The second drawing car 5 is located at the start 12 a of therun 12 which is assigned to it. The clamps 7 of the drawing car 5 areopened. The drawing car 4 is moved along the run by a moving field whichhas been produced by the coils 9 of the inductor and thus draws thedrawing material 3 which has been clamped in the clamps 7. As soon asthe drawing car 4 approaches the start 12 a of the run, which isassigned to the second drawing car 5, it automatically feeds the drawingmaterial 3 into the second drawing car 5. The second drawing car 5accelerates and as soon as it has reached the speed of the first drawingcar 4, or of the drawing material 3, the jaws 7 of the second drawingcar 5 are closed. The two drawing cars 4 and 5 now simultaneously drawthe drawing material 3 to the end 11 b, 12 b of their respective runs11, 12. As soon as the first drawing car 4 has reached the end 11 b ofits run 11, the clamps 7 of the first drawing car 4 are opened and thesecond drawing car 5 alone assumes drawing of the drawing material 3.

The drawing car 4, with the clamps 7 opened, travels back to the start11 a of its run 11 (FIG. 3) while the second drawing car draws thedrawing material to the end 12 b of its run. As soon as the firstdrawing car has reached the start 11 a of its run 11, the feed of thedrawing material 3 into the drawing machine is ended. The open-loop orclosed-loop control unit in the following cycles now triggers the coils9 of the inductor such that there is no overlapping area 13 between theruns 11 and 12. The runs 11 and 12 rather abut one another without anoverlapping area, as already described using FIG. 4.

1. A rectilinear drawing machine for drawing material with at least twomovable drawing cars which are driven on a path, one run being assignedto each drawing car, the path has an inductor and the drawing cars havean armature of the linear motor, the drawing cars have field coils, thecoils being entirely or partially superconductive.
 2. A rectilineardrawing machine as claimed in claim 1, wherein the runs are fixed suchthat the runs overlap.
 3. A rectilinear drawing machine as claimed inclaim 1, wherein the runs are fixed during operation of the rectilineardrawing machine.
 4. A rectilinear drawing machine as claimed claim 1,wherein the rectilinear drawing machine has closed-loop or open-loopcontrol for establishing the runs.
 5. A rectilinear drawing machine, fordrawing material as claimed in claim 1, wherein the at least two movabledrawing cars driven with a linear motor.
 6. A rectilinear drawingmachine as claimed in claim 5, wherein the path has an inductor and thedrawing cars have an armature of the linear motor.
 7. A rectilineardrawing machine as claimed in claim 6, wherein the inductor has coilswhich are arranged along and/or on the path.
 8. A rectilinear drawingmachine as claimed in claim 7, wherein the rectilinear drawing machinehas open-loop or closed-loop control via which current flow through thecoils is controlled independently of one another, by which the runs ofthe individual drawing cars are controlled.
 9. A process for continuousrectilinear drawing of drawing material, by means of a rectilineardrawing machine with at least two drawing cars, comprising drawing thematerial by means of at least one drawing car along the run assigned tothe drawing car on a path, the oath has an inductor and the drawing carshave an armature of the linear motor, the drawing cars have field coils,the coils being entirely or partially superconductive wherein the runsof the at least two drawing cars are changed during drawing.
 10. Theprocess as claimed in claim 9, wherein in a first cycle, specificallyduring a feed of the drawing material into the drawing machine, runswhich are fixed such that the runs overlap.
 11. The process as claimedin claim 10, wherein in the overlapping area of the runs the end of thedrawing material is transferred from the first drawing car to the seconddrawing car.
 12. The process as claimed in claim 11, wherein to transferthe drawing material, the first drawing car draws the drawing materialwhich is held beforehand in the area of a drawing die to the start ofthe overlapping area, wherein there the second drawing car picks up theend of the drawing material and with the first drawing car draws thedrawing material to the end of the overlapping area where the firstdrawing car releases the drawing material.
 13. The process as claimed inclaim 12, wherein the second drawing car draws the drawing material toan end of the run of the second drawing car after taking over thedrawing material from the first drawing car.
 14. The process as claimedin claim 12, wherein the run of the first drawing car and/or of thesecond drawing car is changed after release of the drawing material bythe drawing cars for the following cycles.
 15. The process as claimed inclaim 14, wherein the runs of the at least two drawing cars in thefollowing cycles do not overlap.
 16. The process as claimed in claim 9,wherein the rectilinear drawing machine has more than two drawing cars,two of the drawing cars, which are not directly adjacent to one anotherat a time, are moved synchronously toward one another on the path.